Invasion
Whenever a player has a fleet in the orbit of an enemy planet, and if that fleet contains at least 1 invasion ship and soldiers, he may invade the enemy planet. An Army Barracks is required to begin Training Soldiers
Space combat
If there is an enemy fleet, you encounter a space combat before being able to invade. The invasion ship has very poor armour and fleet drive, and with all the expensive soldiers in the fleet it's very important that you provide enough Military Ships cover for this ship.
If you still have invasion ship after combat occurs, you can invade the planet even if there are enemy military ships in its orbit.
Invading
The invasion ship can carry 40,000 
Soldiers. Invading a planet uses all invasion ships in the invading fleet and all soldiers. The workers (idle+busy) and soldiers on the surface of the planet automatically defend against invasions.
The attacker will loose 1 soldier for every 15 hostile workers to kill and 3 soldiers for every 2 defending soldiers.
| Attack & Defence | ||||
| Name | Attack Points | Defence Points | 1x Kills Defending  |
1x Kills Defending |
|---|---|---|---|---|
| Worker |
0 | 2 | - | - |
| Soldier |
30 | 45 | 15 | 0.66666 |
Successful invasion
The invasion is successful if the attacker kills every soldiers and workers in the planet. Then, the attacker takes control of the planet and the resources stored on it.
Enemy ships in the orbit of the planet are not destroyed by invasion, so the combat will continue each turn as long as there are enemy fleets and military ships in at least one side.
Enemy ships that were left in the Ship Yard are destroyed during invasion.
Invasion failure
If the attacker does not have enough soldiers, the invasion fails and the defender keeps control of the planet.
The attacker loses all soldiers and involved invasion ships (invasion ships without soldiers will not be destroyed).
The defender loses soldiers and defending workers, whose numbers depends on the number of attacking soldiers. Workers are killed only after the attacker successfully killed all defending soldiers.
Escaping a planet before invasion
If there are enemy military ships in the orbit of your planet and you also have ships in orbit, a combat will occur in the beginning of each turn. If the enemy ships are powerful enough, they can destroy any ship you send to the planet. But it does not prevent you to leave the planet with ships and some resources, as long as the enemy don't invade you (for example if there is no enemy invasion ship yet). Because the combat happens in the beginning of the turn, you can freely create fleets during the turn and give them order to leave the planet. Once the turn ends, the fleets can go away so they are not there next turn when the combat happens.